Issue: mining ships stuck if planet/moon being mined is colonized or an extraction base is constructed there (base with mining/extractor equipment)

Steps to reproduce: Find a planet that is currently being mined by mining ships. Colonize planet. Observe mining ships. Note cargo of extracted resources does not increase, ever.

Proposed change: Periodically check mining/gas miner ships that their target has not been colonized or a mining base built at it, both of which cause them to cease operations and be stuck there.

Query: When multiple mining ships target a single body, do they all extract the resources, or just one at a time? It seems that the mechanics allow for only one - in which case this should also be considered for revision.